I checked out an e-book from my local library (using the ADE version option). I downloaded the .acsm file. When I attempt to add the book to my PC's library or simply open from the .acsm file, I get the above error message.

My library directed me to the OverDrive support folks who directed me to Adobe's support page which was singularly unhelpful. I've de-authorized and re-authorized my ADE. I can't delete and re-download the book. My library doesn't allow this format to be returned early, and I really don't want to have to wait until it expires to get it again in a different format.

I am using ADE version 3.0. My OS is Windows 7 64-bit Home Premium SP1. I use Firefox 55.0.3 (32-bit).